There is interest in a variety of techniques for providing intermittent or continuous electrical power from a power source that utilizes constituents of the environment. In the context of devices implanted in a human or animal, there is a desire to find an energy source that utilizes the body's own chemicals for providing electrical power to the device. This typically includes a mechanism for converting energy stored in chemical compounds in the body to electrical energy. Such devices have been difficult to prepare and implement.
In outdoor situations, solar energy, wind energy, and mechanical vibrations have been used to provide power from the environment. However, because of the diffuse nature of these sources of energy, devices with relatively large footprints are needed to provide the desired energy. Furthermore, these sources of energy are often intermittent and may not be available in all situations. Another potential source of energy is available from chemical energy stored in plants or their residue.
Electrochemical fuel cells have been developed to convert energy stored in chemical compounds to electrical energy. After nearly 50 years of research and development, however, only the hydrogen anode/oxygen cathode fuel cell operates at ambient temperatures. Fuel cells that operate using organic compounds have not been developed, at least in part, because the surfaces of electrocatalysts for the oxidation of organic compounds have not been stabilized. Fouling by intermediate oxidation products, that are strongly bound to the active sites of the catalysts, causes loss of electrocatalyst activity. Thus, there is a need for the development of electrochemical fuel cells that have electrocatalysts that are resistant to fouling and that can operate using compounds found in biological systems.